The invention relates to apparatus and a method for drying at least one strand of plastics material, more particularly those strands which are passed through a cooling bath during the manufacture of plastics granules. Normally, a plurality of strands are treated simultaneously, in side-by-side relationship.
The most diverse apparatus of this kind are already known, all of which however do not work in a satisfactory manner. In a first type of construction, the strands of plastics material are passed over rolls having perforated walls through which air is blown radially outwardly. Especially when higher strand speeds are employed -- high speeds are desirable in view of the economical operation of the entire plant -- the strands are insufficiently dried, since the time during which the perforations in the rolls can operate is shortened, in addition to which the water forms a meniscus between each strand of plastics material and the surface of the roll and is not removed. Furthermore, these perforated rolls act like sirens when rotating at high speed. In a second type of construction, the cooled strands are supported on an endless screen belt and are passed over suction boxes like in a paper-making machine; however, the above-mentioned meniscus formation cannot be prevented, so that the drying is also inadequate in this case.
Finally, it is also known to granulate the strands in a water bath, and to use centrifuges or vibrating screens to separate the cooling water from the granules. This is much too complicated for economical manufacture and also produces an inadequately dried granulated product.